Foam Board Insulation is Great for the Garage

Although foam board insulation can be used in almost any part of a home, this material is particularly well suited for a garage space where exposed walls and ceilings need insulation with ease of installation.

The most obvious reason for installing rigid board insulation in your garage is the heating and cooling efficiency gained by using it. It reduces heat conduction through a garage’s structural supports such as wood and steel wall studs. Another benefit is the materials used in making this insulation act as a vapor barrier, and help eliminate damp walls and floors, cutting down on the chance for mold or mildew to thrive in a closed space. Finally, another not so obvious benefit is soundproofing. If you or your family frequently uses a garage as a workshop with power tools or as a music room, insulation panels are an extremely effective sound buffer. Fewer disturbances in your neighborhood is always a good thing!

polystyrene foam board insulation

Common polystyrene foam board insulation.

As with most home construction materials foam board insulation can be made of almost any accepted material. The most common are made of polystyrene, polyisocyanurate (or “polyiso”), and polyurethane. While somewhat similar in appearance, the R-value between these three types can vary quite a bit. These panels are also solid and formed from the same material throughout. This is not to be confused with certain types of garage door insulation consisting of a foam core or plastic bubble wrap core with a metal foil exterior.  Finally, there are also some environmentally friendly insulation panels that can be made from natural materials such as cellulose (from plants) or pressed, recycled paper. These “green” insulating panels function and install in the same easy manner.

Although some forms of insulation panels are strong enough to support the weight of a person (such as what you might use as a roofing material), for the garage this level of strength and weight carriage is unnecessary.  What is more important is ease of installation and the ability of the material to resist heat conductance.

foam board insulation between studs

Note the carefully taped seams between foam board panels.

Unlike fiberglass insulation (usually found in rolls or batting) there are no itchy glass fibers to embed in your skin. Installation is a simple job of measuring and cutting the insulation panels with a utility knife or small saw. The material is lightweight and can be installed by one person working alone. Foam board insulation is usually placed between the exterior (siding or brick face) and the studs of exterior walls. To stop air infiltration, the boards should be flush and the seams sealed with tape or caulk. Of course, this is only possible when construction is still occurring. As a retro-fit, the panels are easily cut to size and placed between studs much like traditional insulation.

A major consideration in selecting insulation is it “R” value (the number assigned to the material indicating its ability to reflect heat). The greater the R-value of any material, the greater is its ability to retain heat in the interior or to keep exterior heat from coming in.  R-values for this material are expressed usually in whole numbers, with most standard rigid board insulation having R-values of between 3 and 5 per inch of thickness of material. This number is also based on the material’s density – a denser substance may be thinner but can still carry a fairly high R-value. Although there are many rigid board insulation panels in the R-5 and greater range, the standard needs for most homes in temperate climates are in the 3 to 5 R-value range. Each package of panels will be clearly marked.

Pricing is variable. Material composition and R-value greatly affect the cost per square foot for these insulation panels. The higher the R-value, the more expensive the insulation. You should only buy what is absolutely necessary to get the job done. The average density of standard panel insulation is between 1 and 2 pounds per cubic foot. The denser the material the more costly it will be. Owens Corning is one of the best selling brands.

Finally, there is another factor to consider once the garage is thoroughly insulated. The tighter a garage is sealed the more likely that any hazardous chemical vapors can become a more serious problem. As garages tend to accumulate noxious gases (from automobiles or stored solvents), it is perhaps a good idea to install a garage exhaust fan to insure proper ventilation needs are met.

For best performance, although this can be a do-it-yourself job, foam board insulation depends heavily on correct installation. It might be better to have a certified insulation installer do the job if you are not handy with tools.

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